The vast majority of contemporary utility-scale solar thermal power plants and many other thermal energy plants are based on Rankine cycle (steam-turbine) technology using conventional steam-cycle technology. In order to ensure maximum efficiency, the Rankine cycle of these plants typically includes series of steam turbines arranged in order of decreasing operating pressure wherein the exhaust of the highest pressure steam turbines is used as the feed of the next highest pressure steam turbine.
Depending on inlet steam conditions in front of the first steam turbine, as steam is expanded through a series of turbines, the steam exhaust of the steam turbine in front of the lowest pressure turbine may be saturated. This creates the problem of water droplet erosion of blades within the lowest pressure steam turbine. A solution, described in US application number US2011/0247329, is to apply reheat to the exhaust stream so as to ensure only superheated steam is fed to each turbine.
In particular when the energy source is concentrated solar energy utilising direct steam arrangements, reheat and superheat adds significant complexity to the plant. Therefore, despite the advantages of reheat, it may be preferable to design a plant with no or minimal reheat. In such cases, a solution to erosion is desirable.